1. Field of the Invention
The present invention relates to a semiconductor integrated circuit device including a signal processing circuit for performing the signal processing of an imaging apparatus, an imaging apparatus including the semiconductor integrated circuit device, and a radiation imaging apparatus and radiation imaging system that use the semiconductor integrated circuit device. Incidentally, in the present description, it is supposed that a term of radiation includes an electromagnetic wave, an X-ray, an α-ray, a β-ray, a γ-ray, and the like.
2. Description of the Related Art
In an imaging apparatus including a detector including a plurality of pixels arranged in a matrix, an image signal from the detector is processed by using a semiconductor integrated circuit device including a plurality of signal processing circuits arranged in an array, which signal processing circuits process a signal output from the detector by the column. As a representative example of each of the signal processing circuits, an amplifier circuit amplifying a signal from a pixel can be given, here. Japanese Patent Application Laid-Open No. 2003-057350 discloses an imaging apparatus and a radiation imaging apparatus using the imaging apparatus, in which such integrated circuit device are formed on a plurality of semiconductor substrates separately from the detector and are mounted on the detector.
Such an imaging apparatus is required to have the signal processing circuits that operate at low consumption currents in order to suppress the power consumption of the whole apparatus. Moreover, the imaging apparatus is required to increase the dynamic range of the whole apparatus, and is required to have the signal processing circuits having low noise characteristics accordingly. In particular, an imaging apparatus to be used for a medical radiation imaging apparatus is required to process a very small signal in order to lessen the radiation irradiation quantity to a human body, and is required to have the signal processing circuits having lower noise characteristics. In addition, the imaging apparatus to be used for the radiation imaging apparatus is required to have a lower price for the spread thereof. Consequently, the imaging apparatus is also required to increase the number of the signal processing circuits to be integrated on a semiconductor integrated circuit device to decrease the number of the semiconductor integrated circuit device to be used. In addition, the imaging apparatus is also required to prevent the remarkable increase of the chip area of a semiconductor chip constituting a semiconductor integrated circuit device even if the number of the signal processing circuits to be integrated on the semiconductor integrated circuit device is increased. That is, it is required, in the semiconductor integrated circuit including the signal processing circuit for use in the imaging apparatus, to reduce a noise, reduce a power consumption and to reduce an area of the integrated circuit chip.
In order to meet the requirements mentioned above, a bias circuit supplying the operation biases for the amplifier circuits included in the signal processing circuits to perform their amplifying operations to the amplifier circuits fulfills an important role. U.S. Pat. No. 6,456,270 discloses bias circuits supplying bias currents for driving amplifier circuits arranged to be a linear column in an integrated circuit device. In the bias circuits disclosed in U.S. Pat. No. 6,456,270, the transistors on the input sides of the current mirror circuits constituting the bias circuits are arranged to be dispersed into the respective amplifier circuits. The bias circuits including bias current setting lines, power supply lines, and the input side transistors are hereby commonly arranged to the amplifier circuits of all of the signal processing circuits.